The present invention relates to a method and an apparatus in a communication network for customising a location area for each radio mobile terminal in the network by continuously adapting the size and the shape of the location area to that particular behaviour of the terminal in the network.
According to prior art a communication network, also called network or cellular network, has to keep track of the movements of a radio mobile terminal, also called terminal or mobile terminal, to be able to reach the terminal for incoming traffic to the terminal.
This means that when the terminal changes its location in the network it has to inform the network of its new location. This is normally known as location updating or location registration. A location area is defined as an area in which the terminal is able to move around without informing the network of its location. This reduces the number of location updates performed by the terminal as the terminal only has to inform the network when the terminal changes location area.
The larger the location areas are, the fewer location updates are required by the terminal, but more base stations within the location area are involved when the terminal is paged in the network, and vice versa.
The network for example does paging of a terminal in the network when incoming calls to the terminal are to be set-up, whereby the terminal is paged in all cells belonging to the current location area of the terminal.
Periodic registration, also called periodic location updating, is a way for the network to keep track of if a terminal is leaving the coverage area of the network, or to keep track of if a terminal is shut down from the network without informing the network of this. Hereby, the network avoids to page terminals, which are not able to receive the page. Terminals in the network informs the network of their position at predetermined time intervals, even if the terminal has not changed location area and hence the network gets a confirmation of that the terminal still is reachable in the network.
Generally, information that is sent between the terminal and a corresponding basestation in the network comprise circuit switched traffic, like traditional phone calls, and packet data traffic consisting of information in packets.
A location area used for packet data traffic is smaller than a location area used for circuit switched traffic as packet information more generally are sent often and in bursts, a small amount information every time. More location updates are performed by the terminal in the network as the location areas are small but the radio resources consumed by paging decreases with smaller location areas, since fewer basestations take part in the page.
Existing networks today use location areas, which are static and the same for every terminal in the network. These location areas have fixed shapes and sizes, which are fairly adapted to fit an average behaviour of a user of a terminal in the network.
More advanced networks use overlapping location areas, for example in the mobile system PDC, which results in that different terminals in the network use different location areas. Still the overlapping location areas have fixed shapes and sizes.
A problem with this method is that the size of a location area will inevitably be a compromise between the needs of the different terminals in the network.
On research level adaptive methods are used that customise a location area for a specific terminal. Many of them define the location area as a list of cell identities.
A problem with this method is that a lot of data is transferred over the radio interface when the location area definitions are transferred from the network to the terminal.
In another method the cells are assumed to be equal in size and organised in a regular grid pattern. The size of the location area is defined as the number of cells the terminal can traverse before it has to perform a location update in the network.
A problem with this method is that the cells are assumed to be equal in size and organised in a regular grid pattern, which can not be assumed in a real network.
In the patent document WO 94/13114 is disclosed a method for performing location updating in a cellular radio system, wherein a location area is described which is dynamically adaptive and specific for each subscriber station.
A problem with this solution is that only the system is able to calculate location areas for the terminals in the network, wherein needed information must be transferred from the system to the subscriber station every time the location area for a terminal is changed.
Another problem is that multiple location area identities must be broadcasted in every cell by the system, which is a waste of radio resources in the system.
Further, the terminal is not used for collecting statistics or data, wherein the accuracy in the statistics, on which the adaptive location areas are based, may not be so good.
Another problem is that different location areas depending on the type of traffic sent between the terminals and the system or depending on in which area of the network the terminals are located is not used in this method, wherein the method is ineffective and not so flexible.
The patent document U.S. Pat. No. 5,590,398 describes a virtual mobile location area (VMLA) personalised to the habits of a terminal, which location area employs predetermined: grouping of cells arranged in order of likelihood that the terminal will be in the grouping. The historical pattern of the terminal is analysed and superimposed on the existing network to determine an optimum location area for the particular terminal.
A problem with this solution is that only the system is able to calculate location areas for the terminals in the network, wherein needed information must be transferred from the system to the terminal every time the location area for a terminal is changed.
A location update is performed when the terminal reaches a border of a location area, not at every contact between the network and the terminal, which results in that a contact with the network has to be done by the terminal with the only purpose to perform a location update.
Further, the terminal is not used for collecting statistics or data, wherein the accuracy in the statistics, on which the calculations of the location areas are based, may not be so good.
Another problem is that different location areas, depending on the type of traffic sent between the terminals and the system or depending on in which area of the network the terminals are located, is not used in this method, wherein the method is ineffective and not so flexible.
In the patent document WO 95/08902 is disclosed a method of registering a terminal in a cellular system in which cells form registration areas. Individual location areas are formed for one or more terminals with the intention of avoiding an unnecessarily high number of registrations in border areas of the different registration areas. The location area for a given. terminal has the form of a list of registration identities which list is transmitted to the terminal in conjunction with registration.
A problem with this solution is that the transferring of lists results in that a lot of data has to be sent at every registration, which in turn consumes valuable radio resources.
Another problem is that only the system is able to calculate location areas, wherein needed information must be transferred every time a location area is changed.
Further, different location areas depending on the type of traffic sent between the terminals and the system is not used in this method, wherein the method is ineffective and not so flexible.
The problem dealt with by the present invention is to minimise the radio resource consumption caused by paging, location updating and periodic registration of a radio mobile terminal, also called terminal or mobile terminal, in a communication network, also called network or cellular network.
Another problem is to distribute the load caused by location updating of the terminal in the network more evenly between cells in the network.
One intention of the invention is thus to minimise the radio resource consumption caused by paging, location updating and periodic registration of a terminal in the network.
Another intention is to distribute the load caused by location updating more evenly between cells in the network.
The problem is solved essentially by providing each terminal in a network with an adapted location area, customised to the long term or the short term historical movements or behaviour of the terminal in the network. The invention adapts algorithms, which controls the shape, the position and the size of the location area, wherein the location area continuously adapts to the behaviour of the user of the terminal.
More specifically, the problem is solved in the following manner.
The terminal and the network use three different kinds of modes according to the invention. These modes in turn control what kind of location area the terminal should use. The different modes are called session mode, packet mode and transaction mode.
For a specific terminal in the network, the network uses a mode corresponding to the same type of mode as used by the specific terminal.
The duration of the active periods of a communication, also called traffic, sent between the terminal and the corresponding basestation in the network and the duration of the silent periods in between the active periods determines according to the invention what type of mode the terminal and the network should be in.
Three main types of location areas are used according to the invention. The first type of location area is a home location area, which constitute the normal mobility pattern of the terminal in the network.
Algorithms based on the long term historical movements and traffic frequency of the terminal calculates, also called creates below, a home location area for the terminal when the terminal logs on to the network, and this location area is thereafter transferred from the terminal to the network.
The calculated home location area is used by the terminal and the network when the terminal and the network are in the session mode and when the terminal is located within an home area, which constitute the normal mobility pattern of the terminal in the network (i.e. the home location area).
The second type of location area used by the invention is a session mode-fast adaptive location area. Algorithms simultaneously in both the terminal and the network calculate this location area when the terminal and the network enter the session mode and when the terminal is located outside the home area of the terminal (i.e. the latest calculated home location area).
The third type is a fast adaptive location area, which is used for burstlike traffic, like packet data traffic, which area is called a packet mode/transaction mode-fast adaptive location area.
The terminal and the network use the packet mode/transaction mode-fast adaptive location area when the terminal and the network are in the packet mode or the transaction mode, irrespective of where the terminal is located in the network. Algorithms simultaneously in both the terminal and the network calculate the packet mode/transaction mode-fast adaptive location area for the terminal.
The terminal and the network changes dynamically between the three different modes and adapts themselves to the present type of traffic, which as described above determines what type of location area the terminal should use in the network.
One advantage afforded by the invention is that it proposes a location area scheme, which minimises the consumption of radio resources caused by paging, location updating and periodic registration of the terminal in the network.
Another advantage is that the method according to the invention is very flexible and adaptable. The method can dynamically adapt to a variety of users as well as to future changes in communication styles and network usage habits without compromising the efficient usage of radio resources.
Still another advantage is that, since the location area borders can coincide with arbitrary cell borders, the location update load will not be concentrated to a few cells at the border of the location areas as is the case when fixed location areas are used.
Yet another advantage is that, in most cases, the location area can be changed without exchanging any data between the terminal and the network. This is a very radio resource efficient location update.
Still another advantage is that the method according to the invention simultaneously accommodates the different aspects and requirements of circuit switched traffic and packet data traffic. Users of both these basic communication modes will be efficiently handled according to the invention.
Yet another advantage is that no manual configuration is required to create, maintain and modify the location areas. The method is fully automated in that respect.
The invention will now be described in more detail with reference to exemplifying embodiments thereof and also with reference to the accompany drawings.